Dodecaaluminium trimolybdenum dodecaoxide

Endpoint summary

Additional information

No data on bioaccumulation are available for aluminium molybdenum oxide. However, there are reliable data available for different analogue substances.

The environmental fate pathways and ecotoxicity effects assessments for aluminium metal and aluminium compounds as well as for molybdenum metal and molybdenum compounds is based on the observation that adverse effects to aquatic, soil- and sediment-dwelling organisms are a consequence of exposure to the bioavailable ion, released by the parent compound. The result of this assumption is that the ecotoxicological behaviour will be similar for all soluble aluminium and molybdenum substances used in the presented ecotoxicity tests. As aluminium molybdenum oxide has shown to be only slightly soluble in water (pH 4.5, 7d) and poorly soluble in ecotoxicity test media (pH 7.5-8.5, 96h), it can be assumed that under environmental conditions in aqueous media, the components of the substance will be present in a bioavailable form only in minor amounts (Mo) or hardly, if at all (Al). Within this dossier all available data from soluble and insoluble aluminium and molybdenum substances are taken into account and used for the derivation of ecotoxicological and environmental fate endpoints, based on the aluminium ion and molybdenum ion. All data were pooled and considered as a worst-case assumption for the environment. However, it should be noted that this represents an unrealistic worst-case scenario, as under environmental conditions the concentration of soluble Al³⁺and MoO₄^2-ions released from aluminium molybdenum oxide is negligible (Al) or low (Mo), respectively.

Aluminium

In general, metals do not biomagnify unless they are present as, or having the potential to be, in an organic form (e.g. methylmercury). Organometals tend to be lipid soluble, are not metabolized, and are efficiently assimilated upon dietborne exposure.The available evidence shows the absence of aluminium biomagnification acrosstrophic levels both in the aquatic and terrestrial food chains. The existing information suggests not only that aluminium does not biomagnify, but rather that it tends to exhibit biodilution at higher trophic levels in the food chain. More detailed information can be found in the attached document (White paper on waiving for secondary poisoning for Al & Fe compounds final report 02-02-2010. pdf). BCFs for Aluminium can be found to range from quite low (~100) to quite high values (11,000), see attached pdf: White paper for waiving secondary poisoning for iron and Aluminium. This variance can in large part be explained by the difference in exposure conditions for the various studies. The inverse relationship between water and BCF/BAF values limits the ability to describe hazard as a result of the size of the BCF, i.e., the most pristine ecosystems have the highest BCFs. A better approach is to directly assess the concentrations of Al at various trophic levels in the ecosystem. 

Herrmann and Frick (1995) studied the accumulation of aluminium at low pH conditions in benthic invertebrates with time and representing different functional feeding groups (predators and detritus feeders). Invertebrates of different taxa and feeding type were collected in springtime, when acidity and A1 levels mostly increase from seven streams in southern Sweden. Four of the streams typically had pH values of 4 - 4.5 and contained 0.40 - 0.70 mg inorganic A1/L. The other three streams showed pH values around 6 and A1 concentrations of 0.05 mg inorganic A1/l. For most taxa that could be compared, the animals from the most acidic streams (pH 4) contained more A1 than those from the less acid streams (pH 6). At both pH levels there was a clear tendency that predators contained significantly less amounts of aluminium than shredders. The latter results do not support the hypothesis that aluminium can be accumulated along a food chain in an acidic environment.

Molybdenum

Molybdenum is a natural element that is omnipresent in the environment.

Data on aquatic bioaccumulation that were retrieved, suggest that molybdenum bioconcentration through the food chain is negligible: whole body internal concentrations remain below 1 mg/kg at concentration levels up to several mg/L. Reported wholebody BAFs vary more than 2 orders of magnitude, but there is a distinct inverse relationship between exposure concentration and BAF, i. e., decreasing BAFs with increasing Mo levels in the water column. Of all the 27 BCF/BAF reported all below 100 with the exception of one BAF measured for a mollusc exposed to background Mo water concentrations (BAF of 164). The data demonstrates that Mo, like other essential elements, shows homeostatic control of Mo by these organisms. The homeostatic control of Mo is observed to continue to function up to the milligramme range of exposure. Limited information on transfer of Mo through the food chain indicates that molybdenum does not biomagnify in aquatic food chains.

For the terrestrial compartment, Mo concentration ranges in environmental matrices have been compiled. The data includes concentrations of Mo in the environmental compartments, excluding geogenic enriched areas, and at moderate levels below Mo concentrations causing a toxic effect.

This data suggests that Mo is not significantly concentrated from soil to plants, or soil invertebrates with bioconcentration factors (BCF) or bioaccumulation factors (BAF) of < 5, and that there is no further significant increase in concentration from diet to mammals or birds, even including organs such as kidney or liver (diet tissue concentration ratios <10 and even <1 for muscle tissue). This suggests that biomagnification of Mo, if any, is not significant in the terrestrial compartment and foodchain.

Eisler (1989) made a more exhaustive compilation of environmental concentrations of Mo. That review concluded equally that Mo concentrations in plants, mosses and wildlife tissues (liver and kidney included) are well below 10 mg/kg dry weight, excluding legumes (e.g. clover) that contain up to 28 mg/kg dry weight.